There are several ways to do a screen capture. Here are the ways I am aware of.
To Screen Capture:
* Command+Shift+3: Takes a screenshot of the entire screen, and saves it as a PNG file on the desktop.
* Command+Shift+4, then select an area with the cross hairs: Takes a screenshot of the area and saves it as a file on the desktop.
* Command+Shift+4, let up and then hit the space bar, a camera will pop up then click a window: Takes a screenshot of the window you clicked on and saves it as a file on the desktop.
* Command+Control+Shift+3: Takes a screenshot of the screen, and saves it to the clipboard.
* Command+Control+Shift+4, then select an area: Takes a screenshot of an area and saves it to the clipboard.
* Command+Control+Shift+4, let up and then hit the space bar,a camera will pop up, then click a window: Takes a screenshot of a window and saves it to the clipboard.
In Leopard, the following keys can be held down while selecting an area (via Command+Shift+4 or Command+Control+Shift+4):
* Space, to lock the size of the selected region and instead move it when the mouse moves.
* Shift, to resize only one edge of the selected region.
* Option, to resize the selected region with its center as the anchor point .
To cancel you can also hit 'Esc' and get rid of the crosshairs/camera.